Viscometer

ABSTRACT

A rotor driven by a shaft rotated at a fixed speed is subject to the drag of a liquid the viscosity of which is to be measured to apply an axial thrust to the shaft. The shaft is axially displaced against the action of a helical spring and continues to be rotated at a position where the thrust balances the resilience of the spring. A pointer responds to the displacement of the shaft through a cylindrical rack and a pinion to indicate the viscosity of the liquid.

I United States Patent {151 3,

Ohno [451 July 1 l, 1972 VISCOMETER 2,354,299 7/1944 Bays ..73/$9 [72]Inventor: Toshlhlko Ohm, Tokyo, Japan Primary EmmiMFJ R. Prince [73]Assignee: Rlon Kabushlld Knhha, Tokyo, Japan Assistant Examiner-JosephW. Roskos Filed: p 1970 Attorney-Wenderoth, Lmd & Ponack 21 Appl. No.231,548 ABSTRACT A rotor driven by a shaft rotated at a fixed speed issubject to 521 ms. c1. ..73/59 the a quid MW which 51 1 Int. Cl. ..Go1nll/l6 aPP'Y axial sham M is axially disPlac 5a 73/59 aims a Mica Print?and be rotated at a position where the thrust balances the resilience 56of the spring. A pointer responds to the displacement of the I 1 Ramoscued shah through a cylindrical rack and a pinion to indicate the UNITEDSTATES PATENTS viscosity of the q 2,927,457 3/l960 Pye et al. ..73/599Clllm4DrawlngFlguns PITENTEDJHL I 1 1972 FIG.I

INVENTOR TOSHIHIKO G-INO FIG-4 flaz/aumadgr' ma ATTORNEYS VISCOME'I'ERBACKGROUND OF THE INVENTION This invention relates to improvements in aviscometer and more particularly to a viscometer for measuring theviscosity of a liquid by a mechanical element in which a rotor which isan element at the measuring end of the system is immersed and rotated inthe viscous liquid.

One type of the conventional rotary viscometers including a rotor isknown as the Brookfield" type and has a pneumatic motor and a rotorconnected to the motor through a coil spring, wherein the rotor respondsto the drag of a liquid the viscosity of a liquid the viscosity of whichis being measured to effect the corresponding torsion of the coil springwhich is, in turn, detected. That type of viscometer further has agraduated dial rotatable along with the shaft of the motor leading todifficulty with which the reading is effected. In addition, after eachmeasurement a pointer operatively associated with the dial has been heldstationary by a clamp provided for that purpose, whereby a reading iseffected. This leads to inconvenience in resetting after a measurement.

Another type of the conventional rotary viscometers is known as theEpprecht" type and has included a motor, a rotor connected directly tothe motor and means for detecting a reaction torque exerted on the motoritself due to the drag of a viscous liquid being measured. In such atype of viscometer it has been required to suspend the mass involvingthe motor and the rotor with a low torque and yet in a balanced state.Therefore the viscometers have been difficult to manufacture. Both typesof viscometers as above described are also expensrve.

Still another type of rotary viscometer has been previously provided bythe inventor of the present invention and is disclosed in Japanese Pat.No. 303,754 These viscometers are a planetary gear type and aredisadvantageous in that the gearings involved have been required to bemachined with a high accuracy while balancing all the weight about thecenter of rotation.

SUMMARY OF THE INVENTION Accordingly it is an object of the invention toprovide a new and improved rotary viscometer which has a simpleconstruction and is inexpensive to manufacture and wherein theabovementioned disadvantages of the conventional viscometers areeliminated.

The invention accomplishes this object by the provision of a viscometercomprising a driving shaft longitudinally movable and rotated at apredetermined fixed speed of rotation, a spindle disposed substantiallyperpendicularly to the driving shafi to be rotated by the latter, ameasuring end element connected to the spindle at one end and immersedin a liquid the viscosity of which is to be measured, the measuring endelement as it is rotated being subject to a torque due to the drag ofthe liquid, and a resilient element for exerting a resilient forcelengthwise of the driving shaft, characterized by means for axiallyapplying a thrust to the driving shaft in response to the torqueprovided by the measuring end element to displace the driving shaftagainst the action of the resilient element, and means for detecting thedisplacement of the driving shaft.

Preferably the thrust applying means may comprise a worm member mountedon the driving shaft and a worm gear connected to the spindle at theother end to mesh with the worm member while the detecting means isarranged to indicate the position of the driving shaft where the thrustapplied to the latter shaft balances the resilient force provided by theresilient element.

Advantageously the detecting means may include a cylindrical rackmounted on the driving shaft, a pinion engaging the rack mounted on thedriving shaft, a pinion engaging the rack and a pointer connected to thepinion to convert the longitudinal displacement of the driving shaft toan angular displacemom of the pointer.

The resilient element may conveniently apply to the pinion a forcetending to rotate it in the direction opposite to the direction in whichthe pinion is rotated through the displacement of the driving shaft.

BRIEF DESCRIPTION OF THE DRAWING The invention will become more readilyapparent from the following detailed description taken in conjunctionwith the accompanying drawing in which:

FIG. I is a perspective view of a viscometer constructed in accordancewith the principles of the invention with parts cut away;

FIG. 2 is a fragmental perspective view of a modification of theinvention;

FIG. 3 is a plan view, partly in longitudinal section of a modificationof the cylindrical rack shown in FIG. 1; and

FIG. 4 is a plan view illustrating another form of the detection andindication device shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawingand FIG. I in particular, it is seen that a frame 10 of any suitablemetallic material such as brass or zinc includes an upright end wall I0aextending from one end and another upright wall 10b extending from theintermediate portion and parallel to the end wall. An electric miniaturemotor 12 is mounted on end wall 104 and extends through the end wallwith the longitudinal axis thereof substantially parallel to the frame.The motor 12 is adapted to be rotated at a predetermined fixed speed ofrotation. A rotary shaft extending from the motor I2 substantiallyparallel to and above the frame 10 has fixedly secured thereon a spurgear 14. A driving shaft I6 extends through the walls 100 and b inparallel relationship to the rotary motor shaft and is rotatablysupported by a pair of bearings 18 and 20 fitted into the wallsrespectively. The driving shaft 16 has a longitudinally elongated gear22, a worm 24 and a collar 26 mounted thereon in spaced relationship andin the named order starting from the end wall 100. The gear 22 mesheswith the gear 14 and the worm 24 meshes with a hoiizontally disposedworm gear 28 rigidly secured on one end of a spindle 30 looselyextending through the frame 10 and substantially perpendicular to thedriving shaft 16. The spindle 30 has rigidly secured to the other end arotor 32 forming a measuring end element to be immersed in a liquid theviscosity of which is to be measured contained in a measuring vessel 34.

A resilient element 36 shown in FIG. I as being a helical spring isdisposed around the driving shaft 16 between the collar 26 and theintermediate wall Mb. The driving shaft I6 is provided on that portionthereof projecting beyond the wall 10b with a cylindrical rack 38engaging a pinion 40. A pointer 42 is mounted on a shaft 44 for thepinion 40 and is adapted to swing above a graduated dial 46. The drivingshaft I6 has a righthand extremity I6E as viewed in FIG. I opposed to aleaf spring 48 and normally there will be a predetermined spacingtherebetween.

The leaf spring 48 has disposed at one end an electric contact 50normally engaging an electric stationary contact SI. The leaf spring 48is electrically connected at the other end to one side of an electricsource 52 through a normally open switch 54. The source 52 iselectrically connected on the other side to the contact 51 through themotor 12. Thus the contacts 50 and SI provides a normally closed switch.

Since liquids may be acidic or alkaline, the rotor 32, the shaft 30, thedriving shaft 16, the collar 26 and the spring 36 are preferably of anysuitable anti-corrosive metallic mate rial such as a stainless steel andthe bearings I8 and 20, the gears 14, 22 and 28, the worm 24 and thecylindrical rack 38 are preferably of any suitable plastic such aspolyacetal resin. The pointer 42 may be of brass or stainless steel andthe dial 46 may be of aluminum.

With the components in their positions illustrated in FIG. I, the switch54 can be closed to rotate the motor 12 and therefore the gear 14 at apredetermined fixed speed of rotation in the direction of the arrow 60shown in FIG. 1. This rotational movement of the gear 14 is transmittedthrough the gear 22 to the driving shaft 16 thereby to rotate it at apredetermined fixed speed of rotation in the direction of the arrow 62shown in the same FIG. Therefore the worm 24 on the driving shaft 16rotates the gear 28 and hence the rotor 32 in the direction of the arrow64 shown on the spindle 30 in FIG. I. Then the rotating rotor 32 issubjected to a viscous resistance or a drag of the particular liquid theviscosity of which is being measured. That is, the rotor is subject to atorque proportional to the viscosity of the liquid in the direction ofarrow 66 shown in FIG. 1. Thus the gear 28 is subject to that torque inthe direction of arrow 68 shown in FIG. 1 to apply an axial thrust tothe worm 24 in the direction of arrow 70 shown in the same FIG. Thatthrust serves to move the driving shaft 16 toward the wall b against theaction of the helical spring 36. Then the spring 36 is compressed inresponse to the movement of the driving shaft l6 and the driving shaft16 continues to be rotated at the fixed speed at its position where theresilience provided by the spring 36 has balanced the thrust.

The axial displacement of the driving shaft 16 causes the cylindricalrack 38 to be longitudinally moved to rotate the pinion 40 in thedirection of the arrow 72 shown in FIG. 1 through an angle correspondingto the displacement of the rack 38 and therefore of the shafi 12.Accordingly the pointer 42 is rotated through the same angle above thedial 46. With the dial 46 graduated in terms of viscosity, the viscosityto be measured can be directly read by that graduation on the dial 46coinciding with the moved pointer 42.

If the rotor 32 is subject to a torque sufficient to swing the pointer42 outside of the scale on the dial 46, then the extremity 16E of thedriving shaft 16 abuts against the leaf spring 48 to separate thecontact 50 from the contact 51 whereupon the circuit for energizing themotor 12 is opened to stop the motor. This ensures that the motor 12 isprevented from being overloaded.

A modification of the invention is illustrated in FIG. 2 wherein likereference numerals designate the components identical or correspondingto those shown in FIG. 1. The gear 14 operatively coupled to the motor12 is longitudinally elongated and the mating gear 22 is relatively thinalthough this is not essential. Also, the cylindrical rack 38 is mountedon that portion disposed between the frame walls Illa and b of thedriving shaft 16. Therefore the pinion 40 and the associated componentsare in different positions from those shown in FIG. 1.

The arrangement of FIG. 2 is different from that shown in FIG. I mainlyin that the shaft 44 of the pinion 40 has mounted at one end a pulley 56made, for example of aluminum while a length of cord 58 of stainlesssteel or linen yarn has one end portion wrapped around the pulley 56with the one end fixed to the latter and the other end connected to oneend of the helical spring 36 having the other end suitably anchored tothe frame wall 100. Therefore the helical spring 36 is not disposedaround the driving shaft 16. It is noted that all the rotating membershave their directions of rotation opposite to those shown in FIG. I.

In the embodiment illustrated, the spring 36 serves to maintain thelength of cord 58 in a tensioned state tending to rotate the pulley 56in the counterclockwise direction as viewed in FIG. 2.

As in the arrangement of FIG. 1, the rotating rotor 32 is subject to atorque in the direction of arrow 66 shown in FIG. 2 to displace thedriving shaft 16 in the direction of the arrow 68. This displacement ofthe shaft 16 causes the pinion 40 and therefore the pulley 56 to berotated in a direction opposite to the direction in which the spring 36tends to rotate the pulley 56. That is, the pointer 46 will be moved tofurther pull the spring 36. Therefore it will be appreciated in thearrangement of FIG. 2 that the displacement of the driving shaft 16balances a torque provided by the spring 36 to tend to rotate the pulley$6. In other respects the arrangement is identical to that shown in FIG.I.

The arrangement of FIG. 2 is advantageous in that the rack 38 alwaysengages the pinion 40 only on one side of their teeth, resulting in theelimination of small vibration of the pointer 42.

FIG. 3 shows an improved form of the cylindrical rack 38. Assuming thatthe rack 38 is always subject to a force tending to move it in therighthand direction as viewed in FIG. 3, the cylindrical rack 38 isrotatably mounted on driving shaft 16 on the leit side as viewed in thesame Figure of a retainer ring rigidly secured on the driving shah 16with a thrust ball hearing 82 threaded onto the shaft 16 therebetween.As shown in FIG. 3, the rack 38 has both end portions in rotationalcontact with the shaft 16 and an intermediate portion 84 having aninside diameter greater than the diameter of the shaft 16.

The arrangement of FIG. 3 is effective for greatly decreasing thefriction occurring between the engaging portions of the rack 38 and themating pinion such as the pinion 40 shown in FIG. 1. This results in adecrease in the load upon the motor 12 and therefore in powerconsumption required to energize the motor [2. It is particularlysuitable in the case the source 52 is a battery.

In order to compensate for any backlash that may occur between the rackand pinion 38 and 40 respectively, the arrangement shown in FIG. 4 canbe used. In FIG. 4 like reference numerals designate the componentsidentical or corresponding to those shown in FIG. 2. In FIG. 4, thepinion 40 also engages another cylindrical rack rigidly mounted on asecond shaft 92 which is, in turn, supported by a pair of opposite framewalls and c for axial movement. The shaft 92 is disposed in parallelrelationship to the driving shaft 16 and has a portion projecting beyondthe end wall 100. A helical spring 36 is disposed around the extensionbetween the extremity thereof and the wall 10c to serve normally to biasthe rack 90 toward the wall 100. In other respects the arrangement issimilar to that shown in FIG. 2.

In operation, the rotating shaft 16 is displaced in the direction of thearrow 70 shown in FIG. 4 to rotate the pinion 40 along with the pointer42 in the clockwise direction as viewed in FIG. 4. Thus the pinion 40displaces the rack 90 and therefore the shaft 92 in the direction of thearrow 74 shown in FIG. 4 against the action of the spring 36 until theshaft 92 reaches such a position that it stops its displacement by meansof the resilience of the spring 36 and continues to be rotated at thefixed speed.

In the arrangement of FIG. 4, the spring 36 always exterts aunidirectional force on the racks 38 and 90 and the pinion 40 to removeany backlash therebetween that may occur between the forward and reversemovements of the rack 38 in response to the viscosity of the liquid.This ensures that the fluctuation of the pointer is minimized.

While the invention has been illustrated and described in conjunctionwith a few preferred embodiments thereof, it is to be understood thatvarious changes and modifications may be made without departing from thespirit and scope of the invention. For example, the resilient element 36may be formed of a combination of a plurality of helical springs toindicate the viscosity in a logarithmic scale. Also, the rack 38, thepinion 40 etc. may be replaced by any suitable mechanical-toelectricaltransducer such as a differential transformer to effect a remoteindication.

What is claimed is:

1. A viscometer comprising a source of electric power, an electric motorcoupled to and energized by said source, a Iongitudinally displaceabledriving shaft connected to and rotated at a predetermined fixed speed bysaid electric motor, a spindle disposed substantially perpendicularly tosaid driving shaft, coupling means coupling said spindle and saiddriving shaft so that said spindle is rotated by said driving shaft, ameasuring end element connected to said spindle and immersed in a liquidthe viscosity of which is to be measured, said measuring end element,when rotated, being subject to a torque due to the drag of the liquid, aresilient element operatively coupled to said driving shaft for exertinga resilient force on said driving shaft in the axial direction thereof,said coupling means being responsive to said torque to which saidmeasuring end element is subjected to axially apply a thrust to saiddriving shaft to longitudinally displace said shaft against the actionof said resilient element, and a detector including a cylindrical rackmounted on said driving shaft, a pinion engaging said rack, and apointer operatively coupled to said pinion to convert the longitudinaldisplacement of said driving shaft to an angular displacement thereofwhich is a measure of the viscosity of said liquid.

2. A viscometer as claimed in claim 1 further comprising a switchadjacent said driving shafl and responsive to said longitudinaldisplacement of said driving shafi, said switch being connected betweensaid motor and said source to connect and disconnect said motor to andfrom said source.

3. A viscometer as claimed in claim 1 wherein said cylindrical rack isrotatably mounted on said driving shaft, and means engaging said rackfor preventing said rack from moving in one of the axial directions ofthe driving shaft.

4. A viscometer as claimed in claim 1 wherein said resilient element isat least one helical spring.

5. A viscometer comprising a source of electric power, an electric motorcoupled to and energized by said source, a longitudinally displaceabledriving shaft connected to and rotated at a predetennined fixed speed ofrotation by said electric motor, a spindle disposed substantiallyperpendicularly to said driving shaft, coupling means coupling saidspindle and said shaft so that said spindle is rotated by said shaft, ameasuring end element connected to said spindle and immersed in a liquidthe viscosity of which is to be measured, said measuring end element,when rotated being subject to a torque due to the drag of the liquid,said means being responsive to said torque to which said measuring endelement is subjected to axially apply a thrust to said driving shaft tolongitudinally displace said shafi, and a detector including acylindrical rack mounted on said driving shaft, a pinion engaging saidrack, a pointer operatively coupled to said pinion to convert thelongitudinal displacement of said driving shaft to an angulardisplacement thereof which is a measure of the viscosity of said liquid,and a resilient element operatively coupled to said pinion to tend torotate the latter in a direction opposite to the direction in which thepinion is rotated through the longitudinal displacement of said drivingshaft.

6. A viscometer as claimed in claim 5 further comprising a switchadjacent said driving shaft and responsive to said longitudinaldisplacement of said driving shaft, said switch being connected betweensaid motor and said source to connect and disconnect said motor to andfrom said source.

7. A viscometer as claimed in claim 5 wherein said cylindrical rack isrotatably mounted on said driving shaft, and means engaging said rackfor preventing said rack from moving in one of the axial directions ofthe driving shaft.

8. A viscometer as claimed in claim 5 wherein said resilient element isat least one helical spring.

9. A viscometer comprising a source of electric power, an electric motorcoupled to and energized by said source, a longitudinally displaceabledriving shaft connected to and rotated at a predetermined fixed speed ofrotation by said electric motor, a spindle disposed substantiallyperpendicularly to said driving shah, coupling means coupling saidspindle and said shaft so that said spindle is rotated by said shah, ameasuring end element connected to said spindle and immersed in a liquidthe viscosity of which is to be measured, said measuring end elementwhen rotated being subject to a torque due to the drag of the liquid,said coupling means being responsive to said torque to which saidmeasuring end element is subjected to axially apply a thrust to saiddriving shaft to longitudinally displace said shaft, a detectorincluding a cylindrical rack mounted on said driving shaft, a pinionengaging said rack and a pointer operatively coupled to said pinion toconvert the longitudinal displacement of said driving element to anangular displacement thereof which is a measure of the viscosity of saidliquid, and backlash compensation means including a second shaftdisposed in parallel relationship to said drivin shaft, a furthercylindrical rack fixedly mounted on sai second shaft and engaging saidpinion on said second shaft to exert a resilient force on the latter inthe axial direction thereof.

* i i ll

1. A viscometer comprising a source of electric power, an electric motorcoupled to and energized by said source, a longitudinally displaceabledriving shaft connected to and rotated at a predetermined fixed speed bysaid electric motor, a spindle disposed substantially perpendicularly tosaid driving shaft, coupling means coupling said spindle and saiddriving shaft so that said spindle is rotated by said driving shaft, ameasuring end element connected to said spindle and immersed in a liquidthe viscosity of which is to be measured, said measuring end element,when rotated, being subject to a torque due to the drag of the liquid, aresilient element operatively coupled to said driving shaft for exertinga resilient force on said driving shaft in the axial direction thereof,said coupling means being responsive to said torque to which saidmeasuring end element is subjected to axially apply a thrust to saiddriving shaft to longitudinally displace said shaft against the actionof said resilient element, and a detector including a cylindrical rackmounted on said driving shaft, a pinion engaging said rack, and apointer operatively coupled to said pinion to convert the longitudinaldisplacement of said driving shaft to an angular displacement thereofwhich is a measure of the viscosity of said liquid.
 2. A viscometer asclaimed in claim 1 further comprising a switch adjacent said drivingshaft and responsive to said longitudinal displacement of said drivingshaft, said switch being connected between said motor and said source toconnect and disconnect said motor to and from said source.
 3. Aviscometer as claimed in claim 1 wherein said cylindrical rack isrotatably mounted on said driving shaft, and means engaging said rackfor preventing said rack from moving in one of the axial directions ofthe driving shaft.
 4. A viscometer as claimed in claim 1 wherein saidresilient element is at least one helical spring.
 5. A viscometercomprising a source of electric power, an electric motor coupled to andenergized by said source, a longitudinally displaceable driving shaftconnected to and rotated at a predetermined fixed speed of rotation bysaid electric motor, a spindle disposed substantially perpendicularly tosaid driving shaft, coupling means coupling said spindle and said shaftso that said spindle is rotated by said shaft, a measuring end elementconnected to said spindle and immersed in a liquid the viscosity ofwhich is to be measured, said measuring end element, when rotated beingsubject to a torque due to the drag of the liquid, said means beingresponsive to said torque to which said measuring end element issubjected to axially apply a thrust to said driving shaft tolongitudinally displace said shaft, and a detector including acylindrical rack mounted on said driving shaft, a pinion engaging saidrack, a pointer operatively coupled to said pinion to convert thelongitudinal displacement of said driving shaft to an angulardisplacement thereof which is a measure of the viscosity of said liquid,and a resilient element operatively coupled to said pinion to tend torotate the latter in a direction opposite to the direction in which thepinion is rotated through the longitudinal displacement of said drivingshaft.
 6. A viscometer as claimed in claim 5 further comprisIng a switchadjacent said driving shaft and responsive to said longitudinaldisplacement of said driving shaft, said switch being connected betweensaid motor and said source to connect and disconnect said motor to andfrom said source.
 7. A viscometer as claimed in claim 5 wherein saidcylindrical rack is rotatably mounted on said driving shaft, and meansengaging said rack for preventing said rack from moving in one of theaxial directions of the driving shaft.
 8. A viscometer as claimed inclaim 5 wherein said resilient element is at least one helical spring.9. A viscometer comprising a source of electric power, an electric motorcoupled to and energized by said source, a longitudinally displaceabledriving shaft connected to and rotated at a predetermined fixed speed ofrotation by said electric motor, a spindle disposed substantiallyperpendicularly to said driving shaft, coupling means coupling saidspindle and said shaft so that said spindle is rotated by said shaft, ameasuring end element connected to said spindle and immersed in a liquidthe viscosity of which is to be measured, said measuring end element,when rotated being subject to a torque due to the drag of the liquid,said coupling means being responsive to said torque to which saidmeasuring end element is subjected to axially apply a thrust to saiddriving shaft to longitudinally displace said shaft, a detectorincluding a cylindrical rack mounted on said driving shaft, a pinionengaging said rack and a pointer operatively coupled to said pinion toconvert the longitudinal displacement of said driving element to anangular displacement thereof which is a measure of the viscosity of saidliquid, and backlash compensation means including a second shaftdisposed in parallel relationship to said driving shaft, a furthercylindrical rack fixedly mounted on said second shaft and engaging saidpinion on said second shaft to exert a resilient force on the latter inthe axial direction thereof.